Systems and methods for sensing and avoiding external objects for aircraft

ABSTRACT

A monitoring system for an aircraft has sensors that are used to sense the presence of objects around the aircraft for collision avoidance, navigation, or other purposes. At least one of the sensors may be configured to sense objects around the aircraft and provide data indicative of the sensed objects. The monitoring system may use information from the sensor and information about the aircraft to determine an escape envelope including possible routes that the aircraft can follow to avoid colliding with the object. The monitoring system may select an escape path based on the escape envelope and control the aircraft to follow the escape path to avoid collision with one or more objects.

CROSS REFERENCE TO RELATED APPLICATION

This application claims Priority to U.S. Provisional Application No.62/503,311, entitled “Systems and Methods for Sensing and AvoidingExternal Objects for Aircraft” and filed on May 8, 2017, which isincorporated herein by reference.

BACKGROUND

Aircraft may encounter a wide variety of collision risks during flight,such as debris, other aircraft, equipment, buildings, birds, terrain,and other objects. Collision with any such object may cause significantdamage to an aircraft and, in some cases, injure its occupants. Sensorscan be used to detect objects that pose a collision risk and warn apilot of the detected collision risks. If an aircraft is self-piloted,sensor data indicative of objects around the aircraft may be used by acontroller to avoid collision with the detected objects. In otherexamples, objects may be sensed and classified for assisting withnavigation or control of the aircraft in other ways.

To ensure safe and efficient operation of an aircraft, it is desirablefor the aircraft to detect objects in the space around the aircraft.However, detecting objects around an aircraft and determining a suitablepath for the aircraft to follow in order to avoid colliding with theobjects can be challenging. As an example, for an aircraft, it ispossible for there to be a large number of objects within its vicinity,and such objects may be located in any direction from the aircraft andmoving in various directions at various speeds. Further, any failure toaccurately detect and avoid an object can be catastrophic. Systemscapable of performing the assessments needed to reliably detect andavoid objects external to the aircraft may be expensive or burdensome todesign or implement.

Improved techniques for reliably detecting and avoiding objects within avicinity of an aircraft are generally desired.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings. The elements of the drawings are not necessarily to scalerelative to each other, emphasis instead being placed upon clearlyillustrating the principles of the disclosure.

FIG. 1 depicts a three-dimensional perspective view of an aircrafthaving an aircraft monitoring system in accordance with some embodimentsof the present disclosure.

FIG. 2 depicts a top perspective view of an aircraft, such as isdepicted by FIG. 1, in accordance with some embodiments of the presentdisclosure.

FIG. 3 is a block diagram illustrating various components of an aircraftmonitoring system in accordance with some embodiments of the presentdisclosure.

FIG. 4 is a block diagram illustrating a sense and avoid element inaccordance with some embodiments of the present disclosure.

FIG. 5 is a block diagram illustrating a mission processing element inaccordance with some embodiments of the present disclosure.

FIG. 6 is a top perspective view of an aircraft, such as is depicted byFIG. 1, in accordance with some embodiments of the present disclosure.

FIG. 7 is a three-dimensional perspective view of an aircraft, such asis depicted by FIG. 1, in accordance with some embodiments of thepresent disclosure.

FIG. 8 is a flow chart illustrating a method for sensing and avoidingexternal objects in accordance with some embodiments of the presentdisclosure.

FIG. 9 is a block diagram illustrating a fleet controller in accordancewith some embodiments of the present disclosure.

FIG. 10 is a block diagram illustrating a sense and avoid element inaccordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure generally pertains to vehicular systems andmethods for sensing and avoiding external objects for aircraft. In someembodiments, an aircraft includes an aircraft monitoring system havingsensors that are used to sense the presence of objects around theaircraft for collision avoidance, navigation, or other purposes. Atleast one of the sensors may be configured to sense objects within thesensor's field of view and provide sensor data indicative of the sensedobjects. The aircraft may then be controlled based on the sensor data.As an example, the speed or direction of the aircraft may be controlledin order to avoid collision with a sensed object, to navigate theaircraft to a desired location relative to a sensed object, or tocontrol the aircraft for other purposes.

When the aircraft monitoring system senses an object that is a collisionthreat, the aircraft monitoring system can generate an escape envelopefor the aircraft. The escape envelope may be based on variousinformation and define a range of possible paths for the aircraft tofollow. The system can generate the escape envelope using informationabout the sensed object, the aircraft, the aircraft's route, or otherinformation. Using sensor data, the system can determine the object'slocation and velocity, and classify the type of object sensed. Thesystem can determine distance between the object and aircraft, as wellas maneuvering capabilities for the object based on the identifiedobject type. The system also can use information about the aircraft,such as its capabilities (e.g., maneuverability), energy budget, oroperating status, to create the escape envelope. The system can also useinformation about the route the aircraft is traveling, such as knownobject locations, airspace restrictions, or weather conditions.

Once the system generates the escape envelope, it may identify andvalidate an escape path that is within the envelope. The escape path mayrepresent a route that the aircraft can follow to safely avoid acollision with the object. The system can select an escape path byaccounting for various information, such as maneuver safety margins oreffects on passenger comfort or cargo integrity. For example, theselected escape path may allow the aircraft to avoid colliding withoutrequiring maneuvers that would otherwise cause undue discomfort to apassenger. The system may validate the escape path, such as based oninformation about the aircraft's current capabilities or operations, andprovide the escape path for the aircraft controller to follow if thesystem determines the path is valid. Otherwise, the aircraft monitoringsystem may use new information to update the escape envelope and selecta new escape path.

FIG. 1 depicts a three-dimensional perspective view of an aircraft 10having an aircraft monitoring system 5 in accordance with someembodiments of the present disclosure. The system 5 is configured to usesensors 20, 30 to detect an object 15 that is within a certain vicinityof the aircraft 10, such as near a flight path of the aircraft 10. Thesystem 5 is also configured to determine information about the aircraft10 and its route. The system 5 can determine a safe escape path for theaircraft 10 to follow that will avoid a collision with the object 15.

Note that the object 15 can be of various types that aircraft 10 mayencounter during flight. As an example, the object 15 may be anotheraircraft, such as a drone, airplane or helicopter. The object 15 alsocan be a bird, debris, or terrain that are close to a path of theaircraft 10. In some embodiments, object 15 can be various types ofobjects that may damage the aircraft 10 if the aircraft 10 and object 15collide. In this regard, the aircraft monitoring system 5 is configuredto sense any object 15 that poses a risk of collision and classify it asdescribed herein.

The object 15 of FIG. 1 is depicted as a single object that has aspecific size and shape, but it will be understood that object 15 mayhave various characteristics. In addition, although a single object 15is depicted by FIG. 1, there may be any number of objects 15 within avicinity of the aircraft 10 in other embodiments. The object 15 may bestationary, as when the object 15 is a building, but in someembodiments, the object 15 may be capable of motion. For example, theobject 15 may be another aircraft in motion along a path that may pose arisk of collision with the aircraft 10. The object 15 may be otherobstacles (e.g., terrain or buildings) posing a risk to safe operationof aircraft 10 in other embodiments.

The aircraft 10 may be of various types, but in the embodiment of FIG.1, the aircraft 10 is depicted as an autonomous vertical takeoff andlanding (VTOL) aircraft 10. The aircraft 10 may be configured forcarrying various types of payloads (e.g., passengers, cargo, etc.).Although the embodiments disclosed herein generally concernfunctionality ascribed to aircraft monitoring system 5 as implemented inan aircraft, in other embodiments, systems having similar functionalitymay be used with other types of vehicles 10, such as automobiles orwatercraft. The aircraft 10 may be manned or unmanned, and may beconfigured to operate under control from various sources. In theembodiment of FIG. 1, the aircraft 10 is configured for self-piloted(e.g., autonomous) flight. As an example, aircraft 10 may be configuredto perform autonomous flight by following a predetermined route to itsdestination. The aircraft monitoring system 5 is configured tocommunicate with a flight controller (not shown in FIG. 1) on theaircraft 10 to control the aircraft 10 as described herein. In otherembodiments, the aircraft 10 may be configured to operate under remotecontrol, such as by wireless (e.g., radio) communication with a remotepilot. Various other types of techniques and systems may be used tocontrol the operation of the aircraft 10.

In the embodiment of FIG. 1, the aircraft 10 has one or more sensors 20of a first type (e.g., cameras) for monitoring space around aircraft 10,and one or more sensors 30 of a second type (e.g., radar or LIDAR) forproviding redundant sensing of the same space or sensing of additionalspaces. In some embodiments, the sensors 20, 30 may sense the presenceof an object 15 within the field of view and provide sensor dataindicative of a location of the object 15. Such sensor data may then beprocessed to determine whether the object 15 presents a collision threatto the vehicle 10. In addition, any of the sensors 20, 30 may compriseany optical or non-optical sensor for detecting the presence of objects,such as a camera, an electro-optical or infrared (EO/IR) sensor, a lightdetection and ranging (LIDAR) sensor, a radio detection and ranging(radar) sensor, or other sensor type. Exemplary techniques for sensingobjects using sensors 20, 30 are described in PCT Application No.PCT/US2017/25592 and PCT Application No. PCT/US2017/25520, each of whichis incorporated by reference herein in its entirety.

FIG. 1 further shows an escape envelope 25 generated by the aircraftmonitoring system 5 in response to detection of the object 15. Theescape envelope 25 defines the boundaries of a region through whichescape paths may be selected. The escape envelope may be based onvarious factors, such as the current operating conditions of theaircraft (e.g., airspeed, altitude, orientation (e.g., pitch, roll, oryaw), throttle settings, available battery power, known system failures,etc.), capabilities (e.g., maneuverability) of the aircraft under thecurrent operating conditions, weather, restrictions on airspace, etc.Generally, the escape envelope 25 defines a range of paths that theaircraft is capable of flying under its current operating conditions.The escape envelope 25 generally widens at points further from theaircraft 10 indicative of the fact that the aircraft 10 is capable ofturning farther from its present path as it travels. In the embodimentshown by FIG. 1, the escape envelope is in the shape of a funnel, butother shapes are possible in other embodiments.

Moreover, when an object 15 is identified in data sensed by sensors 20,30, the aircraft monitoring system 5 may use information about theaircraft 10 to determine an escape envelope 25 that represents apossible range of paths that aircraft 10 may safely follow (e.g., withina pre-defined margin of safety or otherwise). Based on the escapeenvelope 25, the system 5 then selects an escape path within theenvelope 25 for the aircraft 10 to follow in order to avoid the detectedobject 15. In this regard, FIG. 2 depicts an exemplary escape path 35identified and validated by the system 5. In identifying the escape path35, the system 5 may use information from sensors 20, 30 about thesensed object 15, such as its location, velocity, and probableclassification (e.g., that the object is a bird, aircraft, debris,building, etc.). Escape path 35 may also be defined such that theaircraft will return to the approximate heading that the aircraft wasfollowing before it's performed evasive maneuvers.

Note that the escape path 35, although generated based on theinformation indicated by the escape envelope 25, may be validated bysystem 5 to ensure that it is safe based on the most current dataavailable. For example, during the time between detection of an object15 by sensors 20, 30, classification of the object 15, determination ofthe escape envelope 25, and selection of a proposed escape path 25,conditions on which the original escape envelope 25 were based, such asoperational status of a system of the aircraft 10 (e.g., batteries), mayhave changed. In this regard, the system 5 may perform a validationcheck to ensure that no such changes have occurred that may render theproposed escape path 35 unsafe or otherwise less preferable to anotherpotentially available path for the aircraft 10 to follow. The system 5may update the escape envelope 25 based on its detection of changingconditions of the aircraft 10 and determine potential escape paths 35until an escape path 35 for the aircraft 10 is validated.

In addition, it should also be noted that there may be any number ofobjects 15 that pose a collision threat to the aircraft 10 at any giventime. Some of these objects 15 may be “cooperative” in that theycommunicate with the aircraft 10 to convey information about the object15, such as its route, location, heading, speed, size, or otherinformation, and some of the objects may be “uncooperative” in that theydo not communicate information that can be used by the sense and avoidelement 207 or other device or system for assisting with collisionavoidance by aircraft 10. For each sensed object, the sense and avoidelement 207 may determine a threat envelope and select an escape path 35that avoids all of the objects 15 according to the techniques describedherein.

FIG. 3 is a block diagram illustrating various components of an aircraftmonitoring system 205 in accordance with some embodiments of the presentdisclosure. As shown by FIG. 3, the aircraft monitoring system 205 mayinclude a sense and avoid element 207, mission processing element 210, aplurality of sensors 20, 30, and an aircraft control system 225.Although particular functionality may be ascribed to various componentsof the aircraft monitoring system 205, it will be understood that suchfunctionality may be performed by one or more components of the system205 in some embodiments. In addition, in some embodiments, components ofthe system 205 may reside on the aircraft 10 or otherwise, and maycommunicate with other components of the system 205 via varioustechniques, including wired (e.g., conductive), optical, or wirelesscommunication (e.g., using a wireless network or short-range wirelessprotocol, such as Bluetooth). Further, the system 205 may comprisevarious components not specifically depicted in FIG. 3 for achieving thefunctionality described herein and generally performing threat-sensingoperations and aircraft control.

The sense and avoid element 207 of aircraft monitoring system 205 mayperform processing of sensor data and envelope data (e.g., escapeenvelope data) received from aircraft control system 225 to determine anescape path 35. In some embodiments, as shown by FIG. 3, the sense andavoid element 207 may be coupled to each sensor 20, 30, process thesensor data from the sensors 20, 30, and provide signals to the missionprocessing element 210 of aircraft control system 225. The sense andavoid element 207 may be various types of devices capable of receivingand processing sensor data from sensors 20, 30 and envelope data frommission processing element 210. The sense and avoid element 207 may beimplemented in hardware or a combination of hardware andsoftware/firmware. As an example, the sense and avoid element 207 maycomprise one or more application-specific integrated circuits (ASICs),field-programmable gate arrays (FPGAs), microprocessors programmed withsoftware or firmware, or other types of circuits for performing thedescribed functionality. An exemplary configuration of the sense andavoid element 207 will be described in more detail below with referenceto FIG. 4.

In some embodiments, the aircraft control system 225 may include missionprocessing element 210, aircraft controller 220, propulsion system 230,actuator 222, and aircraft sensor 224. The mission processing element210 may be coupled to the sense and avoid element 207 and aircraftcontroller 220, and may be of various types capable of receiving andprocessing data from the sense and avoid element 207 and aircraftcontroller 220, and may be implemented in hardware or a combination ofhardware and software. As an example, the mission processing element 210may comprise one or more application-specific integrated circuits(ASICs), field-programmable gate arrays (FPGAs), microprocessorsprogrammed with software or firmware, or other types of circuits forperforming the described functionality. An exemplary configuration ofthe mission processing element 210 will be described in more detailbelow with reference to FIG. 5.

The aircraft controller 220 may be coupled to each of the missionprocessing element 210, actuator 222, aircraft sensor 224, andpropulsion system 230 for controlling various operations of aircraft 10.In some embodiments, the aircraft controller 220 may perform suitablecontrol operations of the aircraft 10 by providing signals or otherwisecontrolling a plurality of actuators 222 that may be respectivelycoupled to one or more flight control surfaces 223, such as an aileron,flap, elevator, or rudder. Although a single actuator 222 and flightcontrol surface 223 is depicted in FIG. 3 for simplicity ofillustration, various numbers of actuators 222 and flight controlsurfaces 223 are possible to achieve flight operations of aircraft 10.

One or more aircraft sensors 224 may monitor operation and performanceof various components of the aircraft 10 and may send feedbackindicative of such operation and performance to the controller 220.Although a single sensor 224 is depicted in FIG. 3 for simplicity ofillustration, in some embodiments various numbers of aircraft sensors224 possible. As an example, an aircraft sensor 224 may be coupled to anactuator 222 for monitoring the actuator's operation and reporting it tothe aircraft controller 220 for processing. A sensor 224 also may becoupled to sense operation of components of propulsion system 230 andprovide the sensed data to aircraft controller 220. In response to theinformation provided by the aircraft sensor 224 about performance of thesystems of the aircraft 10, the aircraft controller 220 may control theaircraft 10 to perform flight operations.

Further, the propulsion system 230 may comprise various components, suchas engines and propellers, for providing propulsion or thrust toaircraft 10. As will be described in more detail hereafter, when thesense and avoid element 207 senses an object 15 (FIGS. 1, 2), themission processing element 210 may be configured to provide a signal tovehicle controller 220 to control the resources of aircraft controlsystem 225 (e.g., actuators 222 and the propulsion system 230) to changethe velocity (speed and/or direction) of the aircraft 10. As an example,the aircraft controller 220 may control the velocity of the aircraft 10in an effort to follow an escape path 35, thereby avoiding a sensedobject 15. Alternatively, the aircraft controller 220 may navigate to adesired destination or other location based on the sensed object 15.

FIG. 4 depicts a sense and avoid element 207 in accordance with someembodiments of the present disclosure. As shown by FIG. 4, the sense andavoid element 207 may include one or more processors 310, memory 320, adata interface 330 and a local interface 340. The processor 310 may beconfigured to execute instructions stored in memory in order to performvarious functions, such as processing of sensor data from the sensors20, 30 (FIGS. 1, 2) and envelope data from mission processing element310 (FIG. 3). The processor 310 may include a central processing unit(CPU), a digital signal processor (DSP), a graphics processing unit(GPU), an FPGA, other types of processing hardware, or any combinationthereof. Further, the processor 310 may include any number of processingunits to provide faster processing speeds and redundancy, as will bedescribed in more detail below. The processor 310 may communicate to anddrive the other elements within the sense and avoid element 207 via thelocal interface 340, which can include at least one bus. Further, thedata interface 330 (e.g., ports or pins) may interface components of thesense and avoid element 207 with other components of the system 5, suchas the sensors 20, 30 and the mission processing element 210.

As shown by FIG. 4, the sense and avoid element 207 may comprise senseand avoid logic 350, which may be implemented in hardware, software,firmware or any combination thereof. In FIG. 4, the sense and avoidlogic 350 is implemented in software and stored in memory 320 forexecution by the processor 310. However, other configurations of thesense and avoid logic 350 are possible in other embodiments.

Note that the sense and avoid logic 350, when implemented in software,can be stored and transported on any computer-readable medium for use byor in connection with an instruction execution apparatus that can fetchand execute instructions. In the context of this document, a“computer-readable medium” can be any means that can contain or storecode for use by or in connection with the instruction executionapparatus.

The sense and avoid logic 350 is configured to receive data sensed bysensors 20, and 30, classify an object 15 based on the data and assesswhether there is a collision risk between object 15 and aircraft 10.Sense and avoid logic 350 is configured to identify a collision threatbased on various information such as the object's location and velocity.As an example, the sense and avoid logic 350 may estimate a path of theobject 15 based on its sensed position and velocity and compare thecurrent path of the aircraft 10 to the estimated path of the object 15to determine how close the aircraft will likely come to the object 15.If the distance between the two paths is below a threshold, the senseand avoid logic 350 may identify the object 15 as a collision threat.Note that the determination of whether an object 15 is a collisionthreat may be based on other factors, such as the object's size,velocity and maneuverability. For example, a large, fast and highlymaneuverable object 15 may be a collision threat at a greater distancefrom the aircraft 10 relative to an object 15 that is slower, smaller orless maneuverable.

In some embodiments, the sense and avoid logic 350 is configured toclassify the object 15 in order to better assess its possible flightperformance, such as speed and maneuverability, and threat risk. In thisregard, the sense and avoid element 207 may store object data 344indicative of various types of objects, such as birds or other aircraft,that might be encountered by the aircraft 10 during flight. For eachobject type, the object data 344 defines a signature that can becompared to sensor data 343 to determine when a sensed objectcorresponds to the object type. As an example, the object 344 mayindicate the expected size and shape for an object that can be comparedto an object's actual size and shape to determine whether the object 15matches the object type. It is possible to identify not just categoriesof objects (e.g., bird, drone, airplane, helicopter, etc.) but alsospecific object types within a category. As an example, it is possibleto identify an object as a specific type of airplane (e.g., a Cessna172). In some embodiments, the sense and avoid element 207 may employ amachine learning algorithm to classify object types.

For each object type, the object data 344 defines information indicativeof the object's performance capabilities and threat risk. As an example,the object data 344 may indicate a likely or normal speed range andmaneuverability (or other flight performance characteristics) for theobject type, and such information may be used to predict the object'smovements as the aircraft 10 approaches the object 15. In this regard,the sense and avoid logic 350 may determine a threat envelope, similarto the escape envelope 25 described above for aircraft 10, defining theboundaries of a region through which object is likely to pass based onthe performance characteristics indicated for its object type. Theescape path 35 may be selected by the sense and avoid logic 350 suchthat it does not pass through and/or remains at least a specifieddistance from the threat envelope of a detected object 15. In otherembodiments, other techniques for selecting a path to avoid anidentified object based on the flight performance characteristics of itsclassification are possible.

In any event, once the sense and avoid logic 350 identifies andclassifies the object 15, the logic 350 may determine a value, referredto herein as a “risk score,” indicating a degree of risk associated withthe object. The risk score may be based on various factors associatedwith the object, such as its size and performance characteristics. Forexample, objects capable of greater speeds and maneuverability andhaving greater sizes may be associated with higher risk scoresindicating that they pose a greater risk to the aircraft 10. Such riskscore may be used to determine a desired safety margin for the escapepath 35 to be selected. As an example, for an object associated with thegreater risk score, the sense and avoid logic 350 may require a greaterseparation distance between the escape path 35 and the expected path orthreat envelope of the object 15.

As an example, assume that the sense and avoid logic 350 based on datafrom sensors 20, 30 detects an object 15 at a certain location withinthe vicinity of the aircraft's route. If the object is classified as abird (e.g., a goose), the sense and avoid logic 350 may assess arelatively low risk score for the object 15 and determine a relativelysmall threat envelope for the object 15 based on the capabilities of theobject's classification indicated by the object data. In such case, thesense and avoid logic 350 may select an escape path 35 that results in arelatively small deviation from the aircraft's current route bringingthe aircraft 10 relatively close to the identified object 15 as itpasses the object 15.

However, assume that the object 15 is instead classified as ahighly-maneuverable object, such as an aircraft type that is associatedwith high performance characteristics by the object data 344. In suchcase, the threat envelope determined for the object 15 by the sense andavoid logic 350 is likely to be much greater than the one describedabove for the bird due to the higher performance characteristics. Inaddition, the sense and avoid logic 350 is likely to assess a higherrisk score indicating that the object is associated with a greater riskprofile relative to the example described above for the bird. In such anexample, the sense and avoid logic 350 may select an escape path thatresults in a larger deviation from the aircraft's current route relativeto the escape path described above for the bird. Further, since theobject 15 is associated with a greater risk score, the escape path maybe selected such that the distance between the aircraft 10 and thethreat envelope is greater in order to provide a higher safety marginfor avoiding the object 15. In both examples, the actual escape pathselected may be based on other factors, such as the amount of powerremaining or any of the other factors described herein.

Note that, in some embodiments, sense and avoid logic 350 may beconfigured to use information from other aircraft 10 for detecting thepresence or location of objects 15. For example, in some embodiments,the aircraft 10 may be one unit of a fleet of aircraft which may besimilarly configured for detecting objects within a vicinity of theaircraft. Further, the aircraft may be configured to communicate withone another in order to share information about sensed objects. As anexample, the sense and avoid element 207 may be coupled to a transceiver399, as shown by FIG. 3, for communicating with other aircraft. When thesense and avoid element 207 senses an object 15, it may transmitinformation about the object 15, such as the object's type, location,velocity, performance characteristics, or other information, to otheraircraft so that sense and avoid elements on the other aircraft canmonitor and avoid the object 15 according to the techniques describedherein. Further, the sense and avoid element 207 may receive similarinformation about objects 15 detected by other aircraft, and use suchinformation to monitor and avoid such objects 15. In some embodiments,mediation between vehicles may occur via various types of protocols,such as ADS-B beacons.

As described above, the sense and avoid element 207 is configured toreceive data 345, referred to herein as “envelope data,” indicative ofthe escape envelope 25 from the mission processing element 210, and thesense and avoid logic 350 is configured to use the escape envelope 25 topropose an escape path 35 to the mission processing element 210. Notethat the sense and avoid logic 350 may identify an escape path topropose based on various information, including the risk score for theobject 15, the object's location and velocity, and the object'sperformance characteristics, as well as other information relevant toselecting a safe escape path 35 for the aircraft 10. In addition, thesense and avoid logic 350 may propose an escape path that will directaircraft 10 to its previous route to its destination once the sense andavoid logic 350 determines that the object 15 is no longer a collisionthreat.

The sense and avoid logic 350 is configured to process sensor data 343and envelope data 345 dynamically as new data become available. As anexample, when sense and avoid element 207 receives new data from sensors20, 30 or mission processing element 210, the sense and avoid logic 350processes the new data and updates any determinations previously made asmay be desired. The sense and avoid logic 350 thus may update anobject's location, velocity, threat envelope, etc. when it receives newinformation from sensors 20, 30. In addition, the sense and avoid logic350 may receive an updated escape envelope 25 from mission processingelement 210 and may use the updated information to select a new escapepath to propose to mission processing element 210 within the escapeenvelope. Thus, the sensor data 343 and the envelope data 345 arerepetitively updated as conditions change.

FIG. 5 depicts a mission processing element 210 in accordance with someembodiments of the present disclosure. As shown by FIG. 5, the missionprocessing element 210 may include one or more processors 410, memory420, a data interface 430 and a local interface 440. The processor 410may be configured to execute instructions stored in memory in order toperform various functions, such as processing of aircraft data 443 androute data 445. The processor 410 may include a central processing unit(CPU), a digital signal processor (DSP), a graphics processing unit(GPU), an FPGA, other types of processing hardware, or any combinationthereof. Further, the processor 410 may include any number of processingunits to provide faster processing speeds and redundancy. The processor410 may communicate to and drive the other elements within the missionprocessing element 210 via the local interface 440, which can include atleast one bus. Further, the data interface 430 (e.g., ports or pins) mayinterface components of the mission processing element 210 with othercomponents of the system 5, such as the sense and avoid element 207 andthe aircraft controller 220.

As shown by FIG. 5, the mission processing element 210 may comprisemission logic 450, which may be implemented in hardware, software,firmware or any combination thereof. In FIG. 5, the mission logic 450 isimplemented in software and stored in memory 420 for execution byprocessor 410. However, other configurations of the mission logic 450are possible in other embodiments. Note that the mission logic 450, whenimplemented in software, can be stored and transported on anycomputer-readable medium for use by or in connection with an instructionexecution apparatus that can fetch and execute instructions.

The mission logic 450 may be configured to process information, such asaircraft data 443, operational data 444, route data 445, and weatherdata 446, to generate an escape envelope 25 and provide it to the senseand avoid element 207, as described above. The aircraft data 443includes information about the performance characteristics of theaircraft 10, such as its various speeds (e.g., never-to-exceed speed,normal operating speeds for various flight configurations, stall speed,etc.), maneuverability, power requirements, and other information usefulin determining the aircraft's capabilities and flight performance. Theaircraft data 443 may also indicate various information about theaircraft 10, such as weight of at least one passenger or cargo andwhether any passengers are on board the aircraft 10, that might limit orotherwise affect the flight performance characteristics of the aircraft10. In one embodiment, the weight of a passenger or cargo may beautomatically sensed by a sensor 20 or may otherwise be determined, suchas for example input by a user. Note that the aircraft data 443 mayindicate different characteristics for different flight configurations.As an example, the performance characteristics of the aircraft 10 whenall components, such as propellers or engines, are operating is likelydifferent after a failure of one or more components (e.g., propellers),and the aircraft 443 data may indicate performance of the aircraft 10when it is experiencing certain component failures. The aircraft data443 may be predefined based on manufacture specifications or testing ofthe aircraft 443 prior to operation.

The operational data 444 includes information about the currentoperating conditions of the aircraft 10, such as the aircraft's currentheading, speed, altitude, throttle settings, pitch, roll, yaw, fuellevel or battery power, and other operational information. Suchinformation may be received by the mission processing element 210 fromone or more aircraft sensors for sensing the indicated operatingconditions or the aircraft controller 220. The operational data 444 mayalso include information about current failures detected by the system225, such as an electrical (e.g., battery) failure, a failure of aflight control surface 223 or actuator 222, a failure of the propulsionsystem 230 (e.g., a propeller or engine), or a failure of anothercomponent of the aircraft 10.

The route data 445 includes information about the route that theaircraft 10 is flying. As an example, the route data 445 may define thewaypoints to be used for navigating the aircraft 10 to its desireddestination, and the route data 445 may indicate various obstacles orobjects (e.g., buildings, bridges, towers, terrain, etc.) along theroute that may be used for collision avoidance or navigation. The routedata 445 may also indicate the locations of restricted airspace (e.g.,airspace through which the aircraft 10 is not permitted to fly). Theroute data 445 may be updated by the mission logic 450 based oncommunications with remote systems for air traffic control or otherpurposes. As an example, the aircraft 10 may be assigned a block orcorridor of airspace in which the aircraft 10 must remain therebylimiting the possible routes that the aircraft 10 may take to avoid anobject 15. The route data 445 may be predefined and, if desired, updatedby the mission processing element 210 as information about the route issensed, such as new stationary obstacles along the route or new airtraffic control instructions.

The weather data 446 includes information about weather within avicinity of the aircraft 20, such as within several miles of theaircraft 10. The weather data 446 may indicate winds, precipitation,lightning, thunderstorms, icing, and other weather phenomena that mayimpact the flight performance of the aircraft 10. The weather data 446may be generated by an onboard weather radar (not shown) or otherweather sensor, or the weather data 446 may be received wirelessly froma remote location as the aircraft 10 travels. As an example, theaircraft 10 may have a receiver that is configured to receive andprocess weather data from the National Weather Service or other sourceof weather information.

The mission logic 450 is configured to generate an escape envelope 25based on the various information stored in memory 420. In this regard,the mission logic 450 is configured to calculate the range of paths thatthe aircraft 10 is capable of taking based on its current operatingconditions and flight performance characteristics. In this regard, thereare at least some paths that the aircraft 10 is incapable of flying orshould not fly due to performance limitations indicated by the aircraftdata 443 for the current operating conditions indicated by theoperational data 444.

Notably the performance limitations of the aircraft 10 may be impactedby certain operating conditions. For example, if the aircraft 10 isbattery powered, the performance limitations may change as the availablepower in the battery reduces. As an example, if the available powerfalls below a threshold, it may be desirable to limit some maneuversthat would otherwise consume considerable power. In such case, themission logic 450 may limit the escape envelope 25 in order to eliminateat least some paths that would require excessive power under the currentoperating conditions. In this embodiment, the monitoring system 205 mayhave sensors for monitoring the power available or used by a battery andmay determine indicative of an amount of power remaining in the batterybased on such sensors. If such value falls below a threshold, themission logic 450 may limit the escape envelope in order to eliminate atleast some paths.

In addition, as described above, the failure of certain components(e.g., one or more propellers) may impact the aircraft's performancecharacteristics, and the mission logic 450 may limit the escape envelope25 in order to eliminate at least some paths that the aircraft 10 is nolonger capable of flying due to component failures. Further, it may bedesirable to limit the escape envelope 25 based on other factors.

For example, the escape envelope 25 may be limited to eliminate pathswithin the envelope 25 that would undesirably cause the aircraft 10 tofly into restricted airspace indicated by the route data 445 or to flytoo close to a known obstacle indicated by the route data 445. Inaddition, the escape envelope 25 may be limited based on the weatherdata 446 in order to eliminate paths within the envelope 25 that wouldcause the aircraft 10 to fly into an undesired weather phenomena, suchas icing or a thunderstorm. Note that the weather indicated by theweather data 446 may also affect the performance characteristicscalculated by the mission logic 450. As an example, strong winds mightprevent the aircraft 10 from flying at least some paths that wouldotherwise be possible in the absence of wind.

Other factors may similarly affect the boundaries of the escape envelope25. As an example, the weight of the cargo may affect how quickly theaircraft 10 can climb or turn and, thus, affect the range of paths thatthe aircraft may be capable of flying. In addition, when a passenger isonboard the aircraft 10, as indicated by the aircraft data 443, it maybe desirable to limit the escape envelope 25 to eliminate at least somepaths (such as paths requiring a high turn rate) that might cause somediscomfort or anxiety to the passenger.

As noted herein, mission logic 450 is configured to dynamically updatethe escape envelope 25 and provide updated versions to the sense andavoid element 207. In some embodiments, when mission logic 450determines that information has changed to a degree that will affect avalidity of the escape envelope 25, the logic 450 may generate anupdated envelope 25 and provide it to the element 207. The logic 450 maybe configured to perform such operations repeatedly when such changesare detected or as desired.

After the mission logic 450 provides an escape envelope 25 to the senseand avoid element 207 and thereafter receives a proposed escape path 35from the sense and avoid element 207, the mission logic 450 isconfigured to validate the escape path 35 and provide a validated escapepath to the vehicle controller 220. In this regard, the mission logic450 is configured to compare information on which the escape path 35 isbased (e.g., information used to generate escape envelope 25) againstthe most current information available (e.g., updated information inaircraft data 443, operational data 444, route data 445, and weatherdata 446). The logic 450 may use various information to validate theproposed escape path 35, such as updated location and velocity of theobject 15, distance between the aircraft in the object 15, and theoperating conditions of the aircraft 10. As an example, the missionlogic 450 may process aircraft data 443 and determine that aircraft 10has encountered an issue (e.g., battery failure or other componentmalfunction, etc.) that affects energy available to perform themaneuvers required to follow the proposed path 35. Alternatively, thepath may bring the aircraft 10 within a distance relative to currentlocation of the object 15 that falls below a desired threshold or bufferdistance. As noted above, the mission logic 450 is configured todynamically generate and provide updated escape envelopes to the senseand avoid element 207, and is configured to dynamically validate eachproposed escape path 35 received from the element 207. The mission logic450 may receive proposed escape paths and dynamically check viabilityagainst information available to the mission processing element 210.

FIG. 6 is a top perspective view of the aircraft 10 such as is depictedin FIG. 1 in accordance with some embodiments of the present disclosure.The aircraft in FIG. 6 has sensors 20, 30 with ranges 625, 635 thatoverlap for redundant sensing of space around the vehicle 10. As shownby FIG. 6, an overlapping region 660 allows for redundant sensing of theoverlapping area, as well as sensor calibration when an object 15 iswithin the overlapping portion 660. Additional techniques for performingsensor calibration are described more fully in PCT Application No. PCTUS/2017/25592 which is incorporated herein by reference in its entirety.In an exemplary operation of aircraft monitoring system 5, each of thesensors 20, 30 may sense the object 15 and provide data that isindicative of the object's position and velocity to sense and avoidelement 207, as described above. Sense and avoid element 207 (e.g.,logic 350) may process the data from each sensor 20, 30 and may notediscrepancies between information indicated by data from each sensor(e.g., based on sensor data 343 or otherwise). Sense and avoid logic 350further may resolve discrepancies present within data from sensors 20,30 based on various information such as calibration data for each sensor20, 30 that may be stored as sensor data 343 or otherwise in otherembodiments. In this regard, sense and avoid logic 350 may be configuredto ensure that information about objects sensed by a sensor 20 of theaircraft 10 is accurate for use by resources of the system 5 ingenerating an escape envelope and selecting and validating an escapepath, as described above.

FIG. 7 is a three-dimensional perspective view of an aircraft 10 such asis depicted by FIG. 1 in accordance with some embodiments of the presentdisclosure. FIG. 7 provides an exemplary illustration of an operation ofthe system 5 in the context of substantially vertical flight operationsof a VTOL aircraft 10 (e.g., during landing or takeoff). The aircraft 10of FIG. 7 has transitioned from a horizontal flight mode (e.g., cruisemode) into a vertical flight configuration (e.g., a landing or takeoffconfiguration). In some embodiments, the aircraft 10 may be configuredto move in a substantially vertical direction, such as for apredetermined distance between a landing or takeoff location and safehorizontal flight altitude.

When the aircraft 10 transitions from its cruise mode into takeoff andlanding mode, aircraft monitoring system 5 may process data from sensorsthat are configured and oriented in the direction of motion of theaircraft 10. In this regard, aircraft 10 and aircraft monitoring system5 are configured to sensor data from sensors 20 that are configured andoriented to sense space that is in the direction of motion of theaircraft 10. Based on the sensed data, the system 5 has generated andprovided an escape envelope 25, and will propose and validate an escapepath 35 that will allow the aircraft 10 to avoid the object 15 whilelanding.

In sensing and avoiding objects 15 in hover flight, the aircraft 10 mayuse the same techniques described above, with an escape envelope 25 thatis oriented in the direction of movement (i.e., vertically). Thus,similar to the techniques described above for forward flight, the senseand avoid element 207 may detect one or more objects 15 that pose acollision risk to the aircraft 10 in hover flight, classify the objects15, determine the performance characteristics of the objects 15, andassess the threat risk of each classified object 15. Using thetechniques described herein, the sense and avoid element 207 may selectan escape path 35 for avoiding the sensed object 15 or make otherdecisions. Notably, one or more of the objects 15 may be on the ground,such as people, animals, or vehicles on or near the landing zone. As anexample, in response to a sensed threat, such as an object 15 on thelanding zone, the sense and avoid element 207 may decide to slow or stopdownward movement, thereby hovering over the landing zone, whilemonitoring the objects 15 to determine when continued movement to thelanding zone is safe. Alternatively, the sense and avoid element 207 mayselect a new landing zone and an escape path 25 that takes the aircraft10 to the new landing zone. Other decisions in response to sensedobjects 15 are possible in other examples.

Note that, in some embodiments, aircraft monitoring system 5 (e.g.,sense and avoid element 207 and mission processing element 210) may beconfigured to perform certain safety and precautionary functionality todecrease a risk of collision with objects during times of increasedexposure to risk presented to the aircraft 10 at takeoff and landing.Aircraft monitoring system 5 (e.g., sense and avoid element 207 andmission processing element 210) may perform a check of sensors whenperforming takeoff and landing maneuvers to confirm that no objects 15are within the path of the aircraft 10. For example, before aircraftcontroller 220 initiates the propulsion system 230, the aircraftmonitoring system 5 may monitor data sensed by one or more sensors 20oriented to sense the area where the aircraft will travel during takeoff(e.g., above the aircraft 10) and, if an object 15 is present within thearea, prevent the aircraft controller 220 from beginning initiation ofthe propulsion system 230 (e.g., starting the propellers, increasingengine power, or otherwise).

In addition, prior to takeoff, the sense and avoid element 207 may checkthe sensor data 343 from the sensors 20, 30 to determine that there isno object on the ground close to the aircraft 10 that might be struck bythe aircraft 10, such as a rotating propeller blade. In this regard, itis possible for a person or animal to wander onto the takeoff area andbe in danger of a strike by the aircraft's propellers when they areturned on. If the sense and avoid element 207 detects a presence of anobject near the aircraft and, in particular, the aircraft's propellersor engines, the sense and avoid element 207 may notify the missionprocessing element 210, which communicates with the aircraft controller220 to disable operation of the propellers or engines until it can beconfirmed that the object is no longer a collision threat.

In some embodiments, the aircraft monitoring system 5 may be configuredto confirm that no objects are present during landing operations. If theaircraft monitoring system 5 determines that an object 15 is within thearea or otherwise present the collision risk to the aircraft 10 duringlanding, the system 5 may take any of several actions to prevent theaircraft 10 from colliding with the object 15. As an example, ifaircraft monitoring system 5 senses that an object 15 is in motion andwill leave the area so that it no longer presents the collision risk tothe aircraft 10, the system 5 may cause the vehicle to wait by hoveringwhile the object 15 continues to travel away from the path of theaircraft 10. However, if the object 15 is stationary within a path ofthe vehicle 10, aircraft monitoring system 5 may determine an escapepath 35 with an escape envelope 25 and provide a signal to the aircraftcontroller 220 to control the aircraft 10 to follow the escape path, asdescribed above.

In several embodiments described above, the sense and avoid element 207and mission processing element 210 are described as separate units, eachhaving its own processor or set of processors to perform the functionsascribed to these elements. However, it is unnecessary for the sense andavoid element 207 and the mission processing element 210 to be separatein other embodiments. As an example, it is possible for the sense andavoid element 207 and mission processing element 210 to be integrated orto share processors or other resources. Separating the functions of thesense and avoid element 207 and the mission processing element 210 ondifferent hardware (e.g., processors) may have certain advantages.

Specifically, using different processors or other hardware for the senseand avoid element 207 and the mission processing element 210 helps tospread the processing burdens associated with these elements acrosshardware resources. In addition, separating the elements 207, 210 helpsto isolate one element from a hardware failure that may be affecting theother element. Furthermore, using different processors or other hardwarefor the sense and avoid element 207 and the mission processing element210 may help to reduce design and manufacturing costs by making aircrafttype transparent to the sense and avoid element 207.

In this regard, the configuration of the sense and avoid element 207 maybe such that it is capable of operating on many different types ofaircraft, and the mission processing element 210 may be configured orprogrammed for the specific type of aircraft 10 on which it resides.Thus, the design of the aircraft control system 225, as well as theaircraft data 443 and operational data 444 stored in the memory 420, maybe tailored to the type of aircraft 10 on which the system 225 resides,whereas the sense and avoid element 207 does not need to be uniquelyconfigured for the aircraft type. That is, the sense and avoid element207 receives an escape envelope 25 that is based on the aircraft type,including the aircraft's capabilities, and is capable of processing theescape envelope 25 to select an escape path 35 within the envelope 25without any knowledge specific to the aircraft's capabilities orconfigurations other than the escape envelope 25 that is provided by themission processing element 210. Thus, the sense and avoid element 207may be used on any of various aircraft without having to redesign thesense and avoid element 207 for the specific aircraft type on which itis used.

An exemplary use and operation of the system 5 in order to sense andavoid objects within a path of the aircraft 10 will be described in moredetail below with reference to FIG. 8. For illustrative purposes, itwill be assumed that an object 15 is within the path of aircraft 10 andfield of view of at least one sensor 20, 30.

At step 802, sense and avoid element 207 may receive data from one ormore sensors 20, 30, and the sense and avoid logic 350 may detect anobject within the sensor data. Based on the information about the object15 sensed by the sensors 20, 30, (e.g., location, velocity, mass, size,etc.), the sense and avoid element 207 may classify the object 15 or, inother words, identify an object type for the detected object 15.Thereafter processing may continue to step 804, where sense and avoidelement 207 may notify the mission processing element 210 that acollision threat has been detected.

At step 806, the mission processing element 210 may determine an escapeenvelope 25 for the aircraft 10. The mission processing element 210 maygenerate the escape envelope 25 as described above and provide it to thesense and avoid element 207 for identification of a proposed escape pathat step 808. After the sense and avoid element 207 has received theescape envelope from the mission processing element 210, the sense andavoid element 207 may process the escape envelope 25 and determine anescape path 35 for the aircraft 10. For example, the escape path 35within the envelope 25 may identify a path for the aircraft 10 to followthat avoids the risk of collision with the object 15, and then returnsthe aircraft 10 to a point that is along the original route to theaircraft's destination. After the sense and avoid element 207 hasdetermined an escape path 35, the sense and avoid element 207 mayprovide the escape path to the mission processing element 210 at step812.

When mission processing element 210 receives the escape path 35, themission processing element 210 may validate the escape path at step 814.Mission processing element 210 may perform the validation by determiningwhether the proposed escape path 35 is within an updated escape envelope25 based on changes to information used to generate the previous escapeenvelope 25. If not, processing returns to step 808 where missionprocessing element 210 provides the updated escape envelope 25 to thesense and avoid element 207. If the proposed path 35 is within theupdated escape envelope 25, mission processing element 210 is configuredto determine the proposed escape path 35 is valid, and processing maycontinue to step 818, where the mission processing element 210 providesinformation indicative of the escape path 35 to aircraft controller 220to control the aircraft 10 to follow the escape path 35. Note that theprocess shown by FIG. 8 may be repeated as may be desired. For example,as the aircraft 10 is following the escape path 35, the aircraft'senvironment and operating conditions may be reassessed and a new escapepath 35 may be selected based on changing conditions, such as movementsby the aircraft 10 and objects 15.

In some embodiments, sensing and avoiding operations may be facilitatedthrough the use of communication with a controller 900 (FIG. 9),referred to hereafter as “fleet controller,” that receives and processesinformation from multiple aircraft 10, collectively referred to hereinas a “fleet” 952. Such fleet controller 952 may be at any location, suchas at a ground-based facility (e.g., an air traffic control tower) orother location. The fleet controller 900 may be various types of devicescapable of receiving and processing information from the aircraft 10.The fleet controller 900 may be implemented in hardware or a combinationof hardware and software/firmware. As an example, the fleet controller900 may comprise one or more application-specific integrated circuits(ASICs), field-programmable gate arrays (FPGAs), microprocessorsprogrammed with software or firmware, or other types of circuits forperforming the described functionality. Similar to the sense and avoidelement 207 and the mission processing element 210 described above, thefleet controller 900 may have one or more CPUs, DSPs, GPUs, FPGAs orother types of processing hardware. As shown by FIG. 9, the fleetcontroller 900 may be coupled to at least one transceiver 911 forenabling communication with the aircraft 10 or other systems locatedremotely from the fleet controller 900. In this regard, the fleetcontroller 900 may be in wireless communication with a fleet 952 ofaircraft 10.

Any of the aircraft 10 of the fleet 952 may communicate with the fleetcontroller 900 directly or through other devices (e.g., repeaters) thatmay be positioned at various locations around the vicinity of the fleet952. If desired, the sense and avoid elements 207 of various aircraft 10may communicate with one another to exchange information on sensedobjects 15, as described above. Such sense and avoid elements 207 mayalso serve as repeating, routing or switching functions for messagescommunicated by the aircraft 10, such that the fleet 952 of aircraft 10forms a wireless mesh network. Such mesh network may be used forcommunication between aircraft 10, as a well as communication betweenthe fleet controller 900 and the aircraft 10.

As shown by FIG. 9, the fleet controller 900 also has memory for storingvarious information, such as environment data 920, traffic data 921, andobject data 922. The environment data 920 indicates various informationabout the environment in which the aircraft 10 of the fleet operate. Asan example, the environment data 920 may store information indicatingthe terrain, including ground-based obstacles, such as buildings,bridges, towers, etc., over which the aircraft 10 operate. Theenvironment data 920 may also indicate information about the airspacethrough which the aircraft 10 fly, such as areas of restricted airspace.The environment data 920 may also indicate areas associated with certaincollision risks, referred to herein as “high risk areas.” As an example,the environment data 920 may identify a region associated with a highvolume of traffic, such as an area around an airport, as a high riskarea. Note that such designation may be temporal (e.g., limited tocertain times, such as certain hours of the day or days of the week ormonth). As an example, the traffic in a given area may be high onlyduring certain hours of the day and thus be designated as a high riskarea only during such hours. In another example, an area where fireworksare shot only at certain times may be designated as a high risk area forsuch time periods. The environment data 920 may correlate each high riskarea with information indicating the type of risk (e.g., high traffic orfireworks) associated with the high risk area. Such information may beuseful for assessing the degree of risk that is associated with the areaand whether paths through the area should be selected under certaincircumstances.

If desired, the fleet controller 900 may transmit the environment data920 to the aircraft 10, which may use the data 920 for sense and avoidfunctions. As an example, the sense and avoid element 207 may select adesired path based on the environment data 920. Further, the sense andavoid element 207 may limit, when possible, the selection of escapepaths 35 that pass through high risk areas. In addition, the route data445 (FIG. 5) may be defined or updated at least in part based on theenvironment data 920. As an example, an escape envelope 25 may bedefined to avoid restricted airspace or high risk areas identified bythe environment data 920.

The traffic data 921 indicates information about the aircraft 10 of thefleet 952, such as the location of each aircraft 10, the velocity ofeach aircraft 10, the route of each aircraft 10, the aircraft type ofeach aircraft, and/or other information useful in tracking the aircraft10 and avoiding collisions. Such information may be communicated fromcooperative aircraft to the fleet controller 900. The information aboutone aircraft 10 may also be communicated by another aircraft 10. As anexample, the sense and avoid element 207 of a first aircraft 10 maysense the location of a second aircraft 10 and report such location tothe fleet controller 952, which may compare locations about the secondaircraft 10 from many aircraft 10 to provide a redundancy check to helpensure the integrity and accuracy of the traffic data 921.

The object data 922 indicates information about objects 15, such asother aircraft 10 (whether or not such other aircraft 10 arecooperative), birds, and other types of collision risks. The sense andavoid element 207 of each aircraft 10 within the fleet 952 may transmitto the fleet controller 952 information indicative of the objects 15 bythe sense and avoid element 207, and the fleet controller 952 may thencompile such information into the object data 922 stored at the fleetcontroller 952. The information about the same object 15 from multipleaircraft 10 may be compared to identify and resolve discrepancies inorder to help ensure the integrity and accuracy of the object data 922.Further, the fleet controller 900 may be configured to transmit theobject data 922 to the aircraft 10 of the fleet 952 so that the aircraft10 can update its data so that each aircraft 10 has a consistent andaccurate view of the objects 15 within the environment monitored by thefleet controller 900 and fleet 952.

In some embodiments, the fleet controller 900 may use the environmentdata 920, the traffic data 921, and the object data 922 to define athree-dimensional (3D) map 930 or other type of map indicative of theregion through which the aircraft 10 fly. Such map 930 may indicate thelocations of terrain and ground-based obstacles, as well as thelocations of aircraft 10 and objects 15 in the airspace. The map 930 mayalso include other information associated with the aircraft 10 andobjects 15, such as their velocities, routes, and other information tothe extent that such information is known by the fleet controller 900.The fleet controller 900 may be configured to transmit the 3D map 930 toeach aircraft 10, which may then use the map 930 for collisionavoidance. As an example, the map 930 may be used to select routes andescape paths. Further, data at an aircraft 10 may be updated based onthe map 930 as may be desired.

By communicating information among the aircraft 10, it is possible forone aircraft 10 to learn from and benefit from the experiences orknowledge gained by another aircraft 10. As an example, assume that anew obstacle, such as building or tower is erected, but the aircraft 10of the fleet are unaware of the presence of the obstacle. As a firstaircraft 10 approaches the obstacle, it may sense the obstacle'spresence using sensors 20, 30 and, if necessary, adjust its route inorder to avoid it. If the sense and avoid element 207 classifies theobstacle as a ground-based on obstacle, it may update its route data 445to include the obstacle as part of the terrain defined by such data 445.Thus, future decisions about selecting routes and defining escapeenvelopes 35 may be based on the updated route data 445 therebyfactoring the presence of the obstacle in such decisions.

In addition, the first aircraft 10 may transmit information indicativeof the newly-detected obstacle to the fleet controller 900, which mayupdate the environment data 920 and/or map 930 to include the obstacle.Thus, when the updated environment data 920 or map 930 is distributed tothe other aircraft 10 of the fleet 952, such other aircraft 10 canupdate the route data 445 to indicate the presence of the obstacle.Thus, each aircraft 10 of the fleet 900 can be informed of thenewly-detected obstacle and make control decisions based on thenewly-detected obstacle as appropriate even before such aircraft detectsit with its own sensors 20, 30. As an example, the sense and avoidelement 207 may select a path that avoids the obstacle based on theobstacle's presence even before the obstacle is sensed with theaircraft's sensors 20, 30.

In any event, the information stored at the fleet controller 900 definesboth a risk model and a behavior model associated with the environmentin which the aircraft 10 operate. The risk model indicates areasassociated with elevated levels of risk and also indicates the type ortypes of risks that are associated with each such area. The behaviormodel indicates the locations of aircraft 10 and other objects 15 withinthe monitored region. Both models are temporal in that they change overtime. A given model may be in real time, indicating the types of risksor behaviors that are currently observed, and the model may also definea history from which patterns may be recognized so that risk predictionsand assessments can be accurately made. As an example, by observing ahigher volume of traffic over a certain region, such as near an airport,during a certain time of day, the region may be predicted as a high riskarea for the same period of the day in the future. The behavior and riskmodels determined by the fleet controller 900 may be shared with theaircraft 10 to assist them in making better informed sense and avoiddecisions. Thus, based on the risk and behavior models, an aircraft 10may make better route selection decisions by taking into accountpredicted risks and behaviors so as to avoid certain regions that willlikely be associated with greater risk in the future based on pastpatterns recognized by the fleet controller 900 or otherwise.

As described above, it is possible for the aircraft 10 to use processinghardware in parallel in order to perform redundant functions forenhancing aircraft safety. FIG. 10 depicts an exemplary embodiment of asense and avoid element 207 where multiple processors 1001-1004 are usedto perform the functionality described herein for the sense and avoidelement 207. FIG. 10 shows one safety processor 1001 and three otherprocessors 1002-1004, referred to hereafter as “general processors,” butthe sense and avoid element 207 may employ any number of safetyprocessors 1001 and other types of processors 1002-1004 in otherembodiments.

The safety processor 1001 is specifically designed for safe operationsuch that it is less likely to have errors or to fail relative to thegeneral processors 1002-1004. In some embodiments, the safety processor1001 may be designed to meet certain processor safety standardspromulgated by the International Organization for Standardization (ISO)or other standards-based organization. In order to meet such standards,the safety processor 1001 may be designed to operate slower than theprocessing speeds of the general processors 1002-1004, which are notdesigned to achieve the same safety qualification or operate with thesame safety margins as the safety processor 1001.

In the embodiment shown by FIG. 10, each general processor 1002-1004 isconfigured to make escape path selections according to the techniquesdescribed herein. Thus, when an object 15 is detected, each processor1002-1004 receives the escape envelope 25 from the mission processingelement 210 and selects an escape path 35 based on the escape envelope25 and other factors, as described above. If desired, each generalprocessor 1002-1004 may use the same algorithm for selecting an escapepath 35, or any general processor 1002-1004 may use a differentalgorithm relative to the other general processors. In some embodiments,each processor 1002-1004 uses machine learning to learn how to selectescape routes 35 based on one or more sets of the training data. Such anon-deterministic method for sense and avoid decisions may result indiscrepancies between the paths that are selected by the generalprocessors 1002-1004 for the same input. Discrepancies may also resultfrom erroneous operation of any of the general processors 1002-1004.

Each general processor 1002-1004 is configured to report its escape pathselection to the safety processor 1001, which then compares the escapepath selections and resolves any discrepancies that may exist betweenthe selections. As an example, if two general processors 1002-1003choose the same escape path or similar escape paths while the otherprocessor 1004 chooses a significantly different escape path, the safetyprocessor 1001 may be configured to use the escape path or one of theescape paths selected by the higher number of processors 1002-1003.After deciding on the escape path to use, the safety processor 1001reports the selected escape path to the mission processing element 210,which validates and uses the selected escape path, as described above.

Note that other sense and avoid decisions by the general processors1002-1004 may be similarly reported to and monitored by the safetyprocessor 1001. As an example, decisions about whether an object 15 isdetected in the data from sensors 20, 30, classifications of the objects15, risk assessments, and other decisions of the sense and avoid element207 described above may be made each general processor 1002-1004, andthe safety processor 1001 may compare such decisions and resolvediscrepancies among them according to any desired algorithm.

In addition, based on the data received from the general processors1002-1004, the safety processor 1001 is configured to monitor theoperation of the general processors 1002-1004 to determine when ageneral processor has failed such that corrective action is desirable.In this regard, the safety processor 1001 performs a watchdog functionfor the general processor 1002-1004. As an example, if the decisions bya given general processor 1002 differ by a certain amount relative tothe decisions by the other general processors 1003-1004 over time, thesafety processor 1001 may determine that the general processor 1002 hasfailed. In other embodiments, other techniques for detecting a failureof a general processor are possible. When a general processor isdetermined to have failed, the safety processor 1001 may be configuredto take corrective action, such as deactivating the failed processor orignoring its output for future control decisions. If the safetyprocessor 1001 is unable to resolve which general processor 1002-1004 isproviding valid data and which has likely failed, the safety processor1001 may take other types of corrective action, such as instructing themission processing element 210 to perform an emergency landing of theaircraft 10 or transition to hover flight in order to reduce thelikelihood that the aircraft 10 will strike an external object 15. Inyet other examples, other types of corrective action are possible.

The foregoing is merely illustrative of the principles of thisdisclosure and various modifications may be made by those skilled in theart without departing from the scope of this disclosure. The abovedescribed embodiments are presented for purposes of illustration and notof limitation. The present disclosure also can take many forms otherthan those explicitly described herein. Accordingly, it is emphasizedthat this disclosure is not limited to the explicitly disclosed methods,systems, and apparatuses, but is intended to include variations to andmodifications thereof, which are within the spirit of the followingclaims.

As a further example, variations of apparatus or process parameters(e.g., dimensions, configurations, components, process step order, etc.)may be made to further optimize the provided structures, devices andmethods, as shown and described herein. In any event, the structures anddevices, as well as the associated methods, described herein have manyapplications. Therefore, the disclosed subject matter should not belimited to any single embodiment described herein, but rather should beconstrued in breadth and scope in accordance with the appended claims.

What is claimed is:
 1. A monitoring system for an aircraft, comprising:a plurality of sensors for sensing an object external to the aircraft;memory for storing data indicative of predefined flight performancecharacteristics of the aircraft; an aircraft control system having atleast one processor configured to determine an escape envelope for theaircraft based on current operating conditions of the aircraft and thedata indicative of the predefined flight performance characteristics ofthe aircraft, the escape envelope defining possible paths that theaircraft may follow to avoid the object; and a sense and avoid elementhaving at least one processor configured to receive first dataindicative of the escape envelope from the aircraft control system andto receive second data indicative of an object sensed by the pluralityof sensors, the at least one processor of the sense and avoid elementconfigured to select a path for avoiding the object based on the escapeenvelope, wherein the aircraft control system is configured to control adirection of the aircraft based on the selected path.
 2. The monitoringsystem of claim 1, wherein the at least one processor of the sense andavoid element is configured to receive information about the object froma second aircraft and to select the path for avoiding the object basedon the information from the second aircraft.
 3. The monitoring system ofclaim 1, wherein the at least one processor of the sense and avoidelement is configured to classify the object based on the second data,thereby determining an object type for the object, and wherein the atleast one processor of the sense and avoid element is configured toselect the path for avoiding the object based on the determined objecttype for the object.
 4. The monitoring system of claim 3, wherein thememory is configured to store third data indicative of predefined flightperformance characteristics for the object type, wherein the at leastone processor of the sense and avoid element is configured to select thepath for avoiding the object based on the third data.
 5. The monitoringsystem of claim 1, wherein the memory is configured to store third dataindicative of a weight of at least one passenger or cargo on theaircraft, wherein the at least one processor of the aircraft controlsystem is configured to determine the escape envelope based on the thirddata.
 6. The monitoring system of claim 1, wherein the at least oneprocessor of the aircraft control system is configured to determine whena component of the aircraft has failed and to determine the escapeenvelope based on a sensed failure of the component.
 7. The monitoringsystem of claim 1, wherein the at least one processor of the aircraftcontrol system is configured to determine a value indicative of anamount of power remaining for a battery of the aircraft and to determinethe escape envelope based on the value.
 8. The monitoring system ofclaim 1, wherein the memory is configured to store third data indicativeof a route for the aircraft, wherein the at least one processor of theaircraft control system is configured to determine the escape envelopebased on the third data.
 9. The monitoring system of claim 1, whereinthe at least one processor of the aircraft control system is configuredto determine the escape envelope based on weather data indicative ofweather in a vicinity of the aircraft.
 10. The monitoring system ofclaim 1, wherein the at least one processor of the aircraft controlsystem is configured to determine whether a passenger is on the aircraftand to determine the escape envelope based on whether a passenger isdetermined to be on the aircraft.
 11. The monitoring system of claim 1,wherein the at least one processor of the aircraft control system isconfigured to validate the path for avoiding the object based on updatedoperating conditions of the aircraft.
 12. A monitoring system for anaircraft, comprising: a plurality of sensors for sensing an objectexternal to the aircraft; an aircraft control system having at least oneprocessor configured to determine an escape envelope for the aircraftbased on current operating conditions of the aircraft, the escapeenvelope defining possible paths that the aircraft may follow to avoidthe object; and a sense and avoid element having a plurality ofprocessors configured to receive first data indicative of the escapeenvelope from the aircraft control system and to receive second dataindicative of an object sensed by the plurality of sensors, each of theplurality of processors configured to select a respective path foravoiding the object based on the escape envelope, wherein the sense andavoid element has a safety processor operating at a processing speedlower than processing speeds for the plurality of processors, andwherein the safety processor is configured to select a path for avoidingthe object based on the paths for avoiding the object selected by theplurality of processors, and wherein the aircraft control system isconfigured to control a direction of the aircraft based on the pathselected by the safety processor.
 13. A monitoring system for anaircraft, comprising: a plurality of sensors for sensing an objectexternal to the aircraft and providing sensor data indicative of theobject; memory for storing data indicative of predefined flightperformance characteristics of the aircraft; at least one firstprocessor configured to determine an escape envelope for the aircraftbased on the current operating conditions of the aircraft and the dataindicative of the predefined flight performance characteristics of theaircraft, wherein the escape envelope defines possible paths that theaircraft may follow to avoid the object; at least one second processorconfigured to select a path for avoiding the object based on the sensordata and the escape envelope; and an aircraft controller configured tocontrol a direction of the aircraft based on the selected path.
 14. Themonitoring system of claim 13, wherein the at least one second processoris configured to receive information about the object from a secondaircraft and to select the path for avoiding the object based on theinformation from the second aircraft.
 15. The monitoring system of claim13, wherein the at least one second processor is configured to classifythe object based on the sensor data, thereby determining an object typefor the object, and wherein the at least one second processor isconfigured to select the path for avoiding the object based on thedetermined object type for the object.
 16. The monitoring system ofclaim 15, wherein the memory is configured to store data indicative ofpredefined flight performance characteristics for the object type,wherein the at least one second processor is configured to select thepath for avoiding the object based on the data indicative of thepredefined flight performance characteristics for the object type. 17.The monitoring system of claim 13, wherein the memory is configured tostore data indicative of a weight of at least one passenger or cargo onthe aircraft, and wherein the at least one first processor is configuredto determine the escape envelope based on the data indicative of theweight of the at least one passenger or cargo.
 18. The monitoring systemof claim 13, wherein the at least one first processor is configured todetermine when a component of the aircraft has failed and to determinethe escape envelope based on a sensed failure of the component.
 19. Themonitoring system of claim 13, wherein the at least one first processoris configured to determine a value indicative of an amount of powerremaining for a battery of the aircraft and to determine the escapeenvelope based on the value.
 20. The monitoring system of claim 13,wherein the memory is configured to store data indicative of a route forthe aircraft, and wherein the at least one first processor is configuredto determine the escape envelope based on the data indicative of theroute.
 21. The monitoring system of claim 13, wherein the at least onefirst processor is configured to determine the escape envelope foravoiding the object based on weather data indicative of weather in avicinity of the aircraft.
 22. The monitoring system of claim 13, whereinthe at least one first processor is configured to determine whether apassenger is on the aircraft and to determine the escape envelope basedon whether a passenger is determined to be on the aircraft.
 23. Themonitoring system of claim 13, wherein the at least one first processoris configured to receive information indicating the selected path fromthe at least one second processor and to validate the selected path foravoiding the object based on updated operating conditions of theaircraft and the data indicative of the performance characteristics ofthe aircraft, and wherein the aircraft controller is configured tocontrol the direction of the aircraft based on the selected path inresponse to validation of the selected path by the at least one firstprocessor.
 24. The monitoring system of claim 15, wherein the at leastone second processor is configured to retrieve information indicative ofperformance capabilities of objects associated with the determinedobject type and to determine a threat envelope for the object based onthe information indicative of the performance capabilities of objectsassociated with the determined object type, and wherein the at least onesecond processor is configured to select the path for avoiding theobject based on the threat envelope.
 25. A monitoring system for anaircraft, comprising: a plurality of sensors for sensing an objectexternal to the aircraft and providing sensor data indicative of theobject; memory for storing data indicative of predefined flightperformance characteristics of the aircraft; a plurality of processors,each of the plurality of processors configured to select a respectivepath for avoiding the object based on the sensor data, the dataindicative of the predefined flight performance characteristics of theaircraft, and the current operating conditions of the aircraft; a safetyprocessor operating at a processing speed lower than processing speedsfor the plurality of processors, the safety processor configured toselect a path for avoiding the object based on the paths for avoidingthe object selected by the plurality of processors; and an aircraftcontroller configured to control a direction of the aircraft based onthe path selected by the safety processor.
 26. A method for use on anaircraft for sensing and avoiding objects, comprising: sensing an objectexternal to the aircraft with sensors on the aircraft; storing in memorydata indicative of flight performance characteristics of the aircraft;sensing current operating conditions of the aircraft with sensors on theaircraft; selecting, with each processor of a plurality of processors onthe aircraft, a respective path for avoiding the object based on thesensing the object, the data indicative of the flight performancecharacteristics of the aircraft, and the sensing the current operatingconditions; selecting with a safety processor a path for avoiding theobject based on the paths for avoiding the object selected by theplurality of processors, the safety processor operating at a processingspeed lower than processing speeds for the plurality of processors; andcontrolling a direction of the aircraft based on the path selected bythe safety processor.
 27. A method for use on an aircraft for sensingand avoiding objects, comprising: sensing an object external to theaircraft with sensors on the aircraft; storing in memory data indicativeof predefined flight performance characteristics of the aircraft;sensing current operating conditions of the aircraft with sensors on theaircraft; determining, with at least a first processor on the aircraft,an escape envelope for the aircraft based on the sensing the currentoperating conditions of the aircraft and the data indicative of thepredefined flight performance characteristics of the aircraft, whereinthe escape envelope defines possible paths that the aircraft may followto avoid the object, and wherein the selecting is based on the escapeenvelope; selecting, with at least a second processor on the aircraft, apath for avoiding the object based on the sensing the object and theescape envelope; and controlling a direction of the aircraft based onthe selected path.
 28. The method of claim 27, further comprisingreceiving information about the object from a second aircraft, whereinthe selecting is based on the information from the second aircraft. 29.The method of claim 27, further comprising classifying the object basedon the sensing the object, wherein the selecting is based on theclassifying.
 30. The method of claim 27, further comprising storing, inthe memory, data indicative of predefined flight performancecharacteristics for an object type for the object, wherein the selectingis based on the data indicative of the predefined flight performancecharacteristics for the object type.
 31. The method of claim 27, furthercomprising storing, in the memory, data indicative of a weight of atleast one passenger or cargo on the aircraft, wherein the determiningthe escape envelope is based on the data indicative of the weight of theat least one passenger or cargo.
 32. The method of claim 27, furthercomprising determining when a component of the aircraft has failed,wherein the determining the escape envelope is based on the determiningwhen the component of the aircraft has failed.
 33. The method of claim27, further comprising determining a value indicative of an amount ofpower remaining in a battery of the aircraft, wherein the determiningthe escape envelope is based on the value.
 34. The method of claim 27,further comprising storing, in the memory, data indicative of a routefor the aircraft, wherein the determining the escape envelope is basedon the data indicative of the route.
 35. The method of claim 27, whereinthe determining the escape envelope is based on weather data indicativeof weather in a vicinity of the aircraft.
 36. The method of claim 27,further comprising determining whether a passenger is on the aircraft,wherein the determining the escape envelope is based on the determiningwhether the passenger is on the aircraft.
 37. The method of claim 27,further comprising validating the path for avoiding the object based onupdated operating conditions of the aircraft.